Currently modems provide command/control mode signaling over a low speed secondary channel superimposed over the primary data channel. Commands sent from one modem to another using a secondary channel are sent at a rate much slower than the primary channel data rate. Moreover, this communication method requires substantial real time processing and filtering to separate the two combined channels. Some other arrangements send command and control information (hereinafter command) via special training sequences. The disadvantage of such a scheme is that a modem's training sequence may not comply with globally accepted CCITT standards.
Thus, there is a continuing need to improve the method by which command and data information are communicated between modems.